Study On The Lithium-ion Batteries' Cyclic And Safety Performances With The Mixed Cathode Materials Of LiNi_1/3Co_1/3Mn_1/3O₂ And LiMn₂O₄

The positive electrode material LiNi_1/3Co_1/3Mn_1/3O₂ is the Lithium-ion battery material which newly emerged in recent years. Because of its'high capacity, good cyclic performance, low cost compared to LiCoO₂ and so on, it hopefully come to be in the application of electric vehicles and hybrid electric vehicles. To greatly improve the performance of lithium-ion batteries, we utilize the advantages of LiNi_1/3Co_1/3Mn_1/3O₂ and LiMn₂O₄ and mixed them to improve the materials'integrative characteristics. The cyclic and safety performance of the mixed cathode materials are researched in the paper.To detect the cyclic performance, the mixed cathode materials are assembled to AA-size batteries. The results show that the discharge capacities of the mixed materials 91 (90%L333+10%LiMn₂O₄),82(80%L333+20%LiMn₂O₄),73 (70%L333+30%LiMn₂O₄)å’Œ55(50%L333+50%LiMn₂O₄) are 147.9mAh/g,137.7mAh/g,134mAh/g and 121mAh/g . The electric performance of 82 and 73 is close to LiCoO₂ which was already put into market. And the capacity fading mechanism of the mixed materials are caused by the deterioration of the cathode materials.The addition of LiMn₂O₄ into LiNi_1/3Co_1/3Mn_1/3O₂ cathode material can improve the safety performance in a deep degree. The overcharge-resistance performance of lithium-ion batteries was detected by overcharging batteries assembled with different cathode materials. MCMB/91,MCMB/82,MCMB/73å’ŒMCMB/55 batteries respectively can pass the over-charging at 3C5V,3C10V,3C15V,3C15V, and among them73 and 55 present higher overcharge stability. The major reason for batteries explosion on overcharging was explained by the thermal stability of different delithiation degrees of different cathode materials.Studies on oven experiment indicate that the addition of LiMn₂O₄ to LiNi_1/3Co_1/3Mn_1/3O₂ can improve the thermal stability of the batteries. The main reason for the batteries explosion was the exothermic reaction caused by L333 at high temperatures.In addition, short-circuit and nail penetration performances of AA-size batteries with different cathode materials show different safety. And the mixed cathode materials are also proved to be safe.